Treatment of hydrocarbon oils



Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE EDWIN R. BIRKHIMER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE ATLANTIC REFINING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPO- RATION OF PENNSYLVANIA TREATMENT or nvnnocamaon OILS No Drawing.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical compositions while of approximately the same-distillation range.

In accordance with my invention, crude I petroleum or petroleum products, particular- 1y oils of substantial viscosity, are separated into various fractions by means of fractional extraction with an aromatic aldehyde or mixture of aromatic aldehydes, or mixture of solvents which contains substantial quantities of an aromatic aldehyde.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as paraflins of the general formula C H olefines of the general formula C,,H .hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/0r ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely, paraffinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in difle'rent proportions. For example, in the parafiin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in I proportions intermediate these two extremes.

As the use of practically all of the petrole- I um oils is almost entirely physical, the above described chemical nature of those oils is im- Application filed May 15, 1931. Serial No. 537,753.

portant in reflecting certain physical characteristics.

The variance in the proportion of the different series of hydrocarbons in paraflinic, naphthenic, and mixed base oils is evidenced by the physical properties of. the various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as compared'with another. For.example, oil derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt Universal at 100 R, will show a specific gravity at 60 F. of about 0.878, Whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf Coast area, will show a specific gravity of about 0.933 at 60 F. The relationship between the viscosity and gravity indicates the degree of the parafiinic or naphthenic character of the oil.

If a given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of the several fractions determined, it will be found that they conform to the general relationship:

G=a+- g 1og(V-38) Chemistry for June, 1928, explains the de-.

termination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the paraflinicity or naphthenicity of an oil, since when a given crude is distilled and fractions thereof are collected, regardless of the fraction upon which the specific gravity and the viscosity are taken,

when such specific gravity and viscosity are substituted in the formula and the viscositygravity constant of the traction calculated, the constant will be substantially the same for each of the several fractions of the crude.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Miltown (Pennsylvania) 0.8067 Burbank (Mid-Continent) 0.8367 Guadalupe (Gulf Coast) 0.8635 Mirando (Gulf Coast) 0.9025

- aldehyde may be employed, and are con- ,sidered within the scope of my invention. The various series of hydrocarbons possess a differential solubility in such solvents; the naphthenic hydrocarbons are much more soluble therein than the paraflinic hydrocarbons. By means of extraction with an aromatic aldehyde, and more particularly with benzaldehyde, it is, therefore, possible to effect a partial separation of the naphthenic hydrocarbons from the paraflinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more paraffinic than the original oil and one which is much more naphthenic. By my invention, for example, it is possible to produce an oil of the quality normally obtained from Appalachian crudes, from crudes of the mixed base type from the Mid-Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf Coast area.

In practicing my invention, I prefer to mix the oil fraction to be treated with a suitable proportion of an aromatic aldehyde, and

more particularly with benzaldehyde, at a temperature sufiiciently high so that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature sufficiently low to cause a sep aration of the liquid into a two-layer system, the upper layer being a solution of a relatively small amount of the aromatic aldehyde in the more paraffinic portion of the oil, and the lower layer comprising a solution of the more naphthenic portion of the oil in the aromatic aldehyde. Instead of this heating and cooling to effect extraction, I may simply agitate the mixture of liquids at normal temperatures. Where substantial quantities of solid hydrocarbons belonging to the true parafiin series (C H are present, these solids or waxes remain in the upper layer and may cause it to be solid or semi-solid. Separation of the two layers is then effected, for example, by decantation, and the aromatic aldehyde removed from each of the separated oil layers by vacuum distillation or other suitable procedure, thereby obtaining two oils of similar distillation ranges but of widely different physical characteristics and correspondingly different chemical compositions.

Before removing the aromatic aldehyde from the upper and more paraffinic layer of oil obtained in the above described process, I may add a further quantity of aromatic aldehyde, and repeat the process for an extraction of additional naphthenic bodies from the oil. The extraction may be repeated any desired number of times, thereby producing oils of progressively increasing paraflinicity as evidenced by a decreasing viscosity-gravity constant. In wax-bearing oils, the final undissolved product is a mixture of solid and liquid hydrocarbons. While the exact chemical compositions of these compounds are not known, it isprobable that the liquid hydrocarbons are branched chain hydrocarbons of the paraffin series, Whereas solid bodies are straight chain paraflin hydrocarbons. This product may be further separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes, such as the cold settling process.

In many instances it will be found of advantage to dewax the oil prior to the extraction process, as this expedites the manual operation of the latter.

invention will be further understood from the following specific example:

100 parts of a previously untreated distillate obtained from at Gulf Coast crude oil and having a viscosity of 612 seconds Saybolt Universal at 100 F., a specific gravity of 0.9303, and a consequent viscosity gravity constant of 0.874 was mixed with 100 parts of benzaldehyde and heated to slightly above the temperature of complete miscibility, which in the particular case was approximately 21 C. The homogeneous liquid which resulted was coo ed with agitation to 0 C., and allowed to settle whereupon a two layer system formed. which consisted of-an upper undissolved, oil layer comprising 79 parts of the mixture and a lower layer of oil dissolved in""benzaldehyde comprising approximately 121 parts of the mixture. Af-

ter separation, the layers were each freed 0.916. The undissolved fraction yielded 25 parts of benzaldehyde and 54 parts of an oil having a viscosity of 433 seconds Saybolt Universal at 100 F., and a specific gravity of 0.9053, and a viscosity gravity constant of 0.846.

From this example it will be seen that by one benzaldehyde extraction there may be obtained two oil fractions which are respectively higher in paraflinicity and naphthenicity than the original oil. By repetition of the extraction process upon the benzaldehyde undissolved fraction, oils may be obtained which are increasingly paraflinic, as evidenced by progressively decreasing viscosity-gravity constants.

It is evident that my process is practically independent of the particular nature or source of the crude oil, and that there may be produced thereby oils of desired characteristics from oils which heretofore have not been used as a source of oils of such desired characteristics. For example, my process may be employed to produce from petroleum of a mixed base type such as would, on normal batch distillation, give a residuum with a viscosity of 150 seconds Saybolt Universal at 210 F. with a specific gravity of 0.928 or more, a lubricating stock with a viscosity at 210 F., of 150 seconds Saybolt Universal, or more, and a specific gravity not higher than 0.910. This latter combination of properties is typical of cylinder stocks produced from Pennsyl- Vania crudes.

In extracting oils containing appreciable amounts of wax, such oils may be dewaxed, for example, by cold settling or centrifuging prior to carrying out the extraction. My

process is operable, however, in the absence of preliminary dewaxing.

Hereinabove, mixtures of solvents have been referred to. It is to be understood that in such mixtures the constituent solvents will not. react with one another, nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts of an aromatic aldehyde.

.For brevity, in the appended claims, the term aromatic aldehyde is employed in a generic sense to include one or a mixture of aromatic aldehydes or a mixture of solvents which contains substantial quantities of aromatic aldehydes.

Also where herein and in the appended claims, an oil is specifically referred to as being viscous. it is to be understood that the oil is of substantial viscosity, i. e., of the order of 50 seconds Saybolt Universal at 100 F., or more.

What I claim is: 1. In the art of refiningmineral oils, the process which comprises separating an oil containing paraifinic and naphthenic hydrocarbons into fractions respectively richer in paratiinic and naphthenic compounds by extracting said oil with an aromatic aldehyde.

2. In the art of refining mineral oils, the process which comprises fractionally extracting an oil containing paraflinic and naphthenic hydrocarbons with an aromatic aldehyde to produce fractions of the oil respectively richer in paraflinic and naphthenic compounds.

3. In the art of refining mineral oils, the process which comprises adding an aromatic aldehyde to an oil containing paraflinic and naphthenic hydrocarbons, heating the mixture to such temperature as to effect solu-, I

tion, cooling the solution to form a two layer system, and separating the upper layer from the lower layer.

4. In the art of refining mineral oils, the process which comprises adding an aromatic aldehyde to an oil containing paraffinic and naphthenic hydrocarbons,'heating the mixture to such temperature as to'eifect solution, cooling the solution to form a two layer system, removing the lower layer, and similarly retreating the upper layer with an aromatic aldehyde.

5. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic 'hydrocarbons into contact with an aromatic aldehyde, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the aromatic aldehyde, separating the solution so formed from the remainder of the oil, and removing the aromatic aldehyde from both portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

6. The process for separating mineral oils containing paraflinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with an aromatic aldehyde, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the aromatic aldehyde, separating the solution so formed from the remainder of the oil, and distilling the aromatic. aldehyde from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in paraflinic and naphthenic hydrocarbons.

7 In the art of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with an aromatic aldehyde, thereby to effect solution of a portion richer in naphthenic hydrocarbons in the aromatic aldehyde, separating the solu tion so formed from the remainder of the oil, and retreating the oil remaining with additional amounts of an aromatic aldehyde.

8. The method of producing paratfinic lubricating oil from mixed base crude which comprises distilling the crude and bringing aportion thereof into contact with benzaldehyde, thereby partially dissolving the oil,

so treated, and removing the benzaldehyde from the treated oil.

9. The process of producing a lubricating stock of specific gravity less than .910 and of Saybolt Universal viscosity greater than 150 seconds at 210 F. from a crude petroleum which on normal distillation yields a residuurn of 150 seconds. Saybolt Universal viscosity at 210 F. and a specific gravity greater than .928, which comprises producing a residuum from the crude etroleum, and extracting said residuum rom said crude petroleum with benzaldehyde.

10. In the art of refining mineral lubricating oil containing paraflinic and naphthenic hydrocarbons, the step of fractionally extracting the oil with benzaldehyde, to ef feet a separation of fractions respectively richer in paraifinic and naphthenic compounds.

11. The process of producing a lubricating stock of specific gravity less than .910 and of Saybolt- Universal viscosity greater than 150 seconds at 210 F. from a crude petroleum which on normal distillation yields a residuum of 150 seconds Saybolt Universal viscosity at 210 F. and a specific gravity greater than .928, which comprises separating a residuum from said crude petroleum and bringing such residuum into contact with benzaldehyde, to effect solution of a portion thereof with benzaldehyde, separating the benzaldehyde solution of oil from the portion which does not dissolve therein, and removing the benzaldehyde from the oil of said solution.

12. In a process for separatinga viscous mineral oil containing parafiinic and naphthenic hydrocarbons into fractions which are respectively richer in naphthenic hydrocarbons and paraflinic hydrocarbons other than wax, the step which comprises extracting the oil with benzaldehyde.

13. In a process for separating viscous mineral oil liquid at ordinary temperature containing .paraflinic and naphthenic hydrocarbons into fractions respectively richer in paraifinic and naphthenic hydrocarbons, the step which comprises extracting the oil with benzaldehyde.

14. In a process for separating a substantially wax free viscous mineral oil containmg paraflinic and naphthenic hydrocarbons into fractions respectively richer in parafiinic and naphthenic hydrocarbons, the step which comprises extracting the oil with benzaldehyde.

15. The process of treating a viscous fraction of a crude oilof one ty containing parafiinic and naphthenic hy rocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different ty e having a greater content of paraiiinic ydrocarbons, which com rises extractmg the viscous fraction with enzaldehyde, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic hydrocarbons.

16. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a paraflinic base crude, which comprises extracting the viscous fraction with benzaldehyde, and separating the oil so treated into portions respectively richer in parafiinic and naphthenic compounds.

17 In the art of refining mineral oils, the process which comprises adding benzaldehyde to a viscous oil liquid at ordinary temperatures containing paraflinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to effect solution, cooling the solution to a temperature sufficient to form two layers respectively richer in naphthenic hydrocarbons and paraliinic hydrocarbons other than wax, and separating the upper layer richer in parafiinic hydrocarbons from the lower layer richer in naph- 

